The present invention relates to a protective arrangement for a piston rod of an excavator hydraulic cylinder and, more particularly, to a protective arrangement in the form of a shell-type protective sleeve fastened to a coupling lug of the piston rod. The protective sleeve is supported on the cylinder housing by a stationary slide ring.
German Patent Document DE-A 37 31 734 describes a protective arrangement of a hydraulic cylinder of a utility vehicle. The arrangement comprises a piston rod covering which, corresponding to the working movements of the hydraulic cylinder or the moving-in and moving-out movements of the piston rod, can be correspondingly displaced with it. A guiding on the cylinder housing for the displacing takes place by way of a flat guide on both sides of the covering constructed has a half-shell. Such a guided displaceable covering, because of the robust operation of utility vehicles, is subjected to a relatively high susceptibility to disturbances since even minor deformations of the covering as a result of outside influences may lead to a jamming. Thus, a functioning of the hydraulic cylinder cannot be fully ensured.
It is an object of the present invention to provide an improved protective arrangement for a piston rod of a hydraulic cylinder which has a sturdy construction and ensures protection even with the effect of outside influences.
This object has been achieved in accordance with the present invention by the provision of a shell-type protective sleeve fastened to the coupling lug of a piston rod of a hydraulic cylinder. The protective sleeve is supported on the cylinder housing by way of a stationary slide ring while resting upon it and encloses the exposed piston rod in a protective manner partially from above.
Principal advantages achieved by the invention are that the shell-type protective sleeve is guided on a slide ring of the cylinder housing, and special flat guides of the type described in German Patent DE-A 37 31 734 are not necessary. Thus, in the case of a deformation of the protective sleeve, no impairment takes place of the functioning of the hydraulic cylinder. The slide ring is preferably made elastically from a plastic material and, by way of a tightening strap, is held on the cylinder housing and thus can by mounted and exchanged in a simple manner.
The protective sleeve of the present invention can be displaced freely on the slide ring corresponding to the working movements of the hydraulic cylinder. This sleeve is subjected to no special tolerance so that, even if the sleeve is damaged, its influence on the hydraulic cylinder and a protective function remains ensured.